A. Technical Field
The present invention relates to an optical switch for an automatic door, and more particularly to an optical switch for automatically opening and closing a door by optically sensing a passing body, such as a human being passing through a certain area at an entrance of a structure.
B. Description of the Prior Art
Light interrupt switches, radar system switches and acoustic system switches which emit a signal where the human beings pass through are conventionally known. However, a light interrupt switch only senses over a limited area. On the other hand, a radar system switch or an acoustic system switch has a disadvantage in that the area detected is not very discrete or definite, and it has been necessary to provide such switches with a light interrupt switch as an auxiliary switch. Furthermore, the above-mentioned area switches merely indicate the presence of objects, and are not able to discriminate the movement direction of human beings etc. moving within the area.